As is well known, where subdivided dry materials are to be discharged through a tapered bottom hopper, plugging sometimes occurs due to the tendency of the product to arch therein, or due to caking from other causes. It has heretofore been common to insert various devices for discharging air or other gas into the material in the hopper to inhibit plugging. Generally it has been considered advisable to direct the air upwardly and away from the walls, although some systems have also directed air downwardly within the hopper. Such systems have ordinarily required a substantial amount of permanently-installed piping. The use of a fabric member through which the air is discharged has been found advantageous. Due to the abrasive effect of the dry materials, it is necessary to replace the fabric member periodically. The present invention has an object to provide an improved and simplified air-operated device for the purpose indicated which can be quickly and easily removed and reinstalled, so as to facilitate servicing. It has been found that effective operation of the device disclosed herein is obtained with air discharge throughout 360.degree. around a horizontal unit which extends substantially across the hopper, between the side walls. The invention is therefore installable without regard to angular orientation. This aspect simplifies both construction and installation, and is related to a further object of the invention. Further objects also include the provision of such a device which is inexpensive, rugged, reliable, compact, and which requires a minimum of piping or conduit means.
Other objects and advantages will become apparent upon consideration of the present disclosure in its entirety.